Is there a way to find out what is in the latest build?
Update

For bleeding edge changes and latest bug reports, even typo fixes you can access these feeds as well

https://twitter.com/BlenderLogs

https://twitter.com/BlenderBugs



There isn't a pretty or detailed view like the release logs for the latest builds, one way you can keep up to date with commits is to go to projects.blender.org developer.blender.org. As a new commit is made, it is updated there along with the revision number, files changed and or features added.

Additionally, if you are on twitter or Google+, Adventures in Blender posts about the latest additions or changes in detail with additional links at times. For example.

You can also now view the shortlog on git.blender.org for a quick summary of commits/fixes.